I have an "update.img" for firmware for my Arnova 9 G2 android tablet.When i transfer it to the tablet and restart it is does not seem to like it and shoes message saving "found an invalid image file '/mnt/storage/update.img'....i obtained the file from Arnova website. What am i doing wrong?SPEC:Model - AN9G2Android v - 2.6.32.27Biuld No. - GINGERBREAD.eng.20111118.10706